Direct contact heat exchanger



March 21, 1967 w. T. OSBORNE I 3,310,103

DIRECT CONTACT HEAT EXCHANGER Original Filed Oct. 8, 1964 I NVEN TOR.

WILLIAM T. OSBORNE.

ATTORNEY.

United States Patent 3,310,103 DIRECT CONTACT HEAT EXCHANGER William T. Osborne, East Syracuse, N.Y., assignor to Carrier Corporation, Syracuse, N.Y., a, corporation of Delaware Original. application Oct. 8, 1964, Ser. No. 402,427, now Patent No. 3,258,933, dated July 1966. Divided and this application Mar. 15, 1966, Ser. No. 534,530 2 Claims. (Cl. I65-141) This application is a division of my copending application Serial No. 402,427, filed Oct. 8, 1964, now Patent No. 3,258,933, granted July 5, 1966. This invention relates to heat exchangers and, more particularly, to a direct contact cooler.

In general, the principle of direct contact cooling of chilled water with a suitable refrigerant has many advantages. manufacturing cost of the refrigeration machine and particularly the required evaporator or cooler, a smaller required refrigerant charge and higher cooling efficiency. A major disadvantage of a direct contact cooler is that the chilled water which is cooled by direct contact with the refrigerant can be expected to carry some refrigerant along with it through a chilled water line to a load, such as a heat exchanger in a room to be cooled. Such carryover of refrigerant may cause flashing or gas blanketing of the heat exchanger and an accompanying reduction of efficiency in the heat exchanger.

The invention is, in brief, directed to a refrigeration system wherein a refrigerant is immiscible with and has a lower boiling point than water and a cooler has a sump for primary chilled water. The cooler is hermetic and has provision for conneciton with a suction line for withdrawing refrigerant vapor. A tube bundle assembly includes a plurality of inner tubes for the circulation of the primary chilled water from the sump with an outer tube about each inner tube for the circulation of secondary chilled water to a load to be cooled. Means is provided for mixing liquid refrigerant and the primary chilled water leaving the tube bundle assembly and spraying the mixed fluids on the tube bundle assembly to cool the secondary chilled water by cooling the sprayed primary chilled water by direct contact with the vaporizing refrigerant, thereby cooling the tube bundle assembly as the primary chilled water passes over the outer tube and into the sump for recirculation through the inner tubes. Thus, the secondary chilled water passing to the load is effectively refrigerant free.

It is a primary object of this invention to provide a new and improved system for providing refrigeration.

Another object is to provide refrigerant free chilled water in a direct contact cooler. A related object is provision of relatively high efficiency in such a cooler. Another related object is provision of such a cooler requiring but a small refrigerant charge.

These and other objects of the invention will be apparent from the following description and the accompanying drawing in which:

FIGURE 1 is a schematic, vertical longitudinal sectional view of a cooler embodying a preferred embodiment of the invention; and

FIGURE 2 is an enlarged sectional view of a tube assembly in a chilled water tube bundle of the cooler, and is taken generally along the line IIII in FIGURE 1.

The invention will be described with reference to preferred chilled mediums which are water, and a preferred refrigerant, which is octafluorocyclobut-ane, commonly referred to as C318 and having a chemical formula C F These fluids are particularly preferred because of their relative immiscibility and because they are inherently highly stable and do not tend to decompose or chemically Among these advantages are a reduction in Ice react With each other or other materials in the system, or cause or promote corrosion or underi'sable lay-products. Also, this refrigerant has alower boiling point than water.- However, other chilled mediums and refrigerants having these desired chemical and physical properties may be utilized within the scope of this invention.

As illustrated in FIGURE 1 of the drawing, a cooler 11 has a closed outer shell 12 communicating with a suction line 13 to a suitable refrigerant compressor (not shown) for withdrawing vaporized refrigerant from the cooler. A chilled water'tube bundle includes a plurality of side-by-side tube bundle assemblies 14 (see also FIG- URE 2). Each assembly includes an inner tube 15 connected with an inlet header 15' for the circulation of primary chilled water received through a supply line 16 from a recirculating water pump 17 having its inlet 18 communicating with a primary chilled water sump 19 in a lower portion of the cooler shell 12. A chilled water line 20 includes an inlet line 21 with a chilled water pump 22 for circulating secondary chilled Water from a load to be cooled and through a header 22 connecting outer tubes 23, one about each inner tube 15. The outer tubes 23 discharge the secondary chilled Water through an outlet header 23' to an outlet line 24 of the chilled water line. As illustrated in the drawing, the outer tubes 23 each envelop a respective one of the inner tubes 15.

Primary chilled Water leaving the inner tubes 15 passes through an outlet header 24' and into a line 25 to a refrigerant liquid inlet line 26 from a suitable flow metering device (not shown) for assing liquid refrigerant from a high side of the system. The water and liquid refrigerant are mixed and pass into a spray header 27 having suitable spray means such as slots 28 for spraying the mixture across the tube bundle assembly 14. Thus, the primary chilled water is cooled by direct contact with the liquid refrigerant which vaporizes upon .being sprayed into the low pressure cooler shell 12. The resultant cooled primary chilled Water and any droplets of liquid refrigerant which havenot vaporized during cooling of the primary chilled water, fall onto the plurality of outer tubes 23 and vaporize as they cool the secondary chilled water passing therethrough. The primary chilled water and residual, unvaporized refrigerant passing across the outer tube bundle 23 collect in the sump 19 for recirculation by the water pump 17 through the inner tube bundle 15 to provide additional cooling of the secondary chilled water by sensible cooling. As illustrated in the drawing, the primary and secondary chilled waters are circulated in opposite directions through their respective tube bundles to obtain an efficient counterflow type sensible heat exchange.

Thus, the secondary chilled Water passing through the chilled water line 20 to the load to be cooled is effectively refrigerant free since it is in a circuit entirely separate from the primary chilled Water and the refrigerant.

While a peferred embodiment of the invention has been described and illustrated, it will be understood that the invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

I claim:

1.- In a heat exchanger, the combination of:

(a) a shell;

(b) a heat exchange tube bundle mounted within said :shell, said tube bundle being of tube-in-tube construction;

(c) a spray header mounted above said tube bundle to spray a mixture of refrigerant and primary fluid medium over said tube bundle;

(d) a refrigerant inlet line connecting with said spray header;

(e) means for circulating a secondaryfiuid medium through said shell and tube bundle;

(f) a sump forming the lower part of said shell beloW the tube bundle for collecting said primary fluid and any unvaporized refrigerant sprayed over the tubes;

(g) means circulating said primary fluid from said sump through a conduit Within each tube of said tube bundle, means connecting said conduits with refrigerant inlet line to permit a mixture of refrigerant and primary fluid to be supplied to the header; and

(h) a refrigerant vapor outlet to discharge vapors from said shell.

2. A heat exchanger according to claim 1 in which the heat exchange tube bundle comprises a plurality of first tubes, secondary fluid headers disposed at opposite References Cited by the Examiner UNITED STATES PATENTS 2,184,285 12/1939 Codling 62-512 X 2,532,328 12/1950 Penning 62394 2,706,408 4/1955 Holbrook 165l41 MEYER PERLIN, Primary Examiner. 

1. IN A HEAT EXCHANGER, THE COMBINATION OF: (A) A SHELL; (B) A HEAT EXCHANGE TUBE BUNDLE MOUNTED WITHIN SAID SHELL, SAID TUBE BUNDLE BEING OF TUBE-IN-TUBE CONSTRUCTION; (C) A SPRAY HEADER MOUNTED ABOVE SAID TUBE BUNDLE TO SPRAY A MIXTURE OF REFRIGERANT AND PRIMARY FLUID MEDIUM OVER SAID TUBE BUNDLE; (D) A REFRIGERANT INLET LINE CONNECTING WITH SAID SPRAY HEADER; (E) MEANS FOR CIRCULATING A SECONDARY FLUID MEDIUM THROUGH SAID SHELL AND TUBE BUNDLE; (F) A SUMP FORMING THE LOWER PART OF SAID SHELL BELOW THE TUBE BUNDLE FOR COLLECTING SAID PRIMARY FLUID AND ANY UNVAPORIZED REFRIGERANT SPRAYED OVER THE TUBES; (G) MEANS CIRCULATING SAID PRIMARY FLUID FROM SAID SUMP THROUGH A CONDUIT WITHIN EACH TUBE OF SAID TUBE BUNDLE, MEANS CONNECTING SAID CONDUITS WITH REFRIGERANT INLET LINE TO PERMIT A MIXTURE OF REFRIGERANT AND PRIMARY FLUID TO BE SUPPLIED TO THE HEADER; AND (H) A REFRIGERANT VAPOR OUTLET TO DISCHARGE VAPORS FROM SAID SHELL. 